Syntheses and Herbicidal Activities of Dithiocarbamates

Several dithiocarbamates were synthesized and their herbicidal activities to radish and barnyardgrass were examined. Some benzyl N, N-dialkyldithiocarbamates such as N-methyl-N-ethyl-, N-methyl-N-n-propyl-, N, N-diethyl- and N, N-diisopropyl-dithiocarbamates showed high activity to these plants, but N-monoalkyl-, N, N-diaryl- and N, N-diaralkyl-dithio- carbamates were not so active. Some substituted benzyl N, N-dialkyldithiocarbamates such as 4-dimethylaminobenzyl N-methyl-N-ethyldithiocarbamate and 4-methoxybenzyl N, N-diethyldithiocarbamate showed high activity to broad-leaved plants. Substituted benzyl N, N-dialkyldithiocarbamates except 4-cyanobenzyl N, N-diisopropyldithiocarbamate, however, were less active to graminaceous plants.     

Conformational restraint is a critical determinant of unnatural nucleotide recognition by protein kinases

This report describes the synthesis of N(4)-(benzyl) AICAR triphosphate, a conformationally restrained analogue of N(4)-(benzyl) ribavirin triphosphate. Both of these nucleotides were evaluated as phosphodonors for wild-type p38MAP kinase and T106G p38MAP kinase, a designed mutant with expanded nucleotide specificity. The conformationally restrained nucleotide, N(4)-(benzyl) AICAR triphosphate, is orthogonal to (not accepted as a substrate by) wild-type p38MAP kinase, in contrast to N(4)-(benzyl) ribavirin triphosphate. Furthermore, N(4)-(benzyl) AICAR triphosphate, is accepted as a substrate by T106G p38MAP kinase, in contrast to N(4)-(benzyl) ribavirin triphosphate. We hypothesize that the presence of an internal hydrogen bond in N(4)-(benzyl) AICAR and its absence in N(4)-(benzyl) ribavirin triphosphate is the main determinant for their differing structure-activity relationships.     

On the specificity of sialidase. Synthesis and properties of N5-acetyl-beta-D-neuraminoylpeptides - AcNeu-Gly-OH, AcNeu-Glu-OH, AcNeu-Phe-OH - and the corresponding alpha-ketosides

By means of the mixed anhydride procedure the benzyl alpha-ketoside of N5-acetyl-D-neuraminic acid was linked to L-glycine, L-glutamic acid and L-phenylalanine. Hydrogenolytic cleavage of the benzyl group resulted in the corresponding free N5-acetyl-beta-D-neuraminoylpeptides. This new class of compounds is no substrate for Vibrio cholerae sialidase. The enzyme does not split the benzyl alpha-ketosides of N5-acetyl-D-neuraminoylpeptides nor is its activity inhibited by these compounds. The results strongly support the assumption that in sialidase substrates the carboxy group must be located close to the ketosidic oxygen. N-(N5-acetyl-beta-D-neuraminoyl)-L-phenylalanine was readily hydrolysed by carboxypeptidase A from bovine pancreas.     

The isolation and characterization of 60 nm vesicles (''nanovesicles'') produced during ionophore A23187-induced budding of human erythrocytes.

1. Penicillin N was synthesized by coupling alpha-amino-alpha-p-nitrobenzyl-N-p-nitro-benzyloxycarbonyl-D-adipate with 6-aminopenicillanic acid benzyl ester, followed by removal of the protecting groups through hydrogenolysis. 2. alpha-Amino-alpha-p-nitrobenzyl-N-p-nitrobenzyloxycarbonyl-D-[5-14C]adipate was prepared by treating alpha-p-nitrobenzyl-N-p-nitrobenzyloxycarbonyl-D-glutamic acid with [14C]diazomethane followed by rearrangement with silver trifluoromethanesulphonate. 3. Coupling of alpha-amino-alpha-p-nitrobenzyl-N-p-nitrobenzyloxycarbonyl-D-[5-14C]adipate with 6-aminopenicillanic acid benzyl ester gave triprotected [10-14C]penicillin N. 4. 3H was introduced at C-6 of the Schiff's base derivative (10) by oxidation followed by reduction with NaB3H4. 5. The so-derived (6 alpha-3H)-labelled Schiff's base was hydrolysed to give 6-amino [6 alpha-3H]penicillanic acid benzyl ester p-toluenesulphonic acid salt, which after coupling as the free amine with alpha-amino-alpha-p-nitrobenzyl-N-pnitrobenzyloxycarbonyl-D-adipate and then hydrogenolysis, yielded [6alpha-3H]penicillin N. 6. Triprotected [10-14C]penicillin N and triprotected [6alpha-3H]penicillin N in admixture were hydrogenolysed to give [10-14C,6alpha-3H]penicillin N.     

Bis(benzyl)polyamine analogs as novel substrates for polyamine oxidase

N,N'-Bis(benzyl)polyamine analogs were found to be substrates for highly purified polyamine oxidase. Metabolism of these analogs was apparently dependent on molecular O2 and resulted in the formation of benzaldehyde, H2O2, and a polyamine analog with free terminal amines. The debenzylation reaction was optimal between pH 9 and 10, identical to the pH optimum for polyamine oxidase activity when N1-acetylspermine was used as the substrate. On a molecular sieve column the debenzylating activity co-eluted with N1-acetylspermine oxidizing activity, at an apparent molecular mass of approximately 65 kDa. The purified enzyme also appeared to have a molecular mass of approximately 65 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Debenzylation of the bis(benzyl)polyamines was competitively inhibited by N1-acetylspermine and N1-acetylspermidine. The specific irreversible inhibitor of polyamine oxidase, N1,N4-bis(buta-2,3-dienyl)butanediamine also inhibited the debenzylation, whereas inhibitors of diamine and monoamine oxidases did not. The evolution of benzaldehyde from bis(benzyl)polyamine analogs by polyamine oxidase allowed the development of a simple rapid spectrophotometric assay for use in the measurement of polyamine oxidase activity in partially purified tissue or cell extracts. Further, metabolism of a bis(benzyl)polyamine analog by polyamine oxidase was found to be an important element in the growth inhibitory properties of the compound in a mouse model of malaria.     

Facile synthesis of benzyl beta-D-galactofuranoside. A convenient intermediate for the synthesis of D-galactofuranose-containing molecules

Benzyl beta-D-galactofuranoside was efficiently obtained from 1,2,3,5,6-penta-O-benzoyl-alpha,beta-D-galactofuranose, via benzyl 2,3,5,6-tetra-O-benzoyl-beta-D-galactofuranoside. Conditions for the O-debenzylation were investigated in order to evaluate the synthetic application of the benzyl group as an anomeric protector of a galactofuranose moiety in synthetic strategies involving galactofuranose.     

Synthesis of a β-D-linked disaccharide from dimeric tri-O-acetyl-2-deoxy-2-nitroso-α-D-glucopyranosyl chloride

Condensation of dimeric 3,4,6-tri-O-acetyl-2-deoxy-2-nitroso-α-D-glucopyranosyl chloride with benzyl alcohol in the presence of N,N,2,4,6-pentamethylaniline or N,N,2,6-tetramethylaniline gave an oximino glycoside that was reduced with lithium aluminum hydride to benzyl 2-amino-2-deoxy-α-D-gluco- and -mannopyranoside hydrochloride that were identified as the N-acetyl derivatives.     

Further studies on the binding of N1-substituted tryptamines at h5-HT6 receptors

N(1)-Arylsulfonyl-substituted analogs of N,N-dimethyltryptamine bind at 5-HT(6) receptors. Replacement of the aryl moiety with similarly hydrophobic alkyl substituents results in decreased affinity, as does replacement of a benzenesulfonyl moiety with a benzyl group. Current findings indicate that an aryl (or substituted aryl) sulfonyl (rather than alkylsulfonyl or benzyl) moiety is optimal for high-affinity binding, and further suggest that the N(1)-benzenesulfonyl- and their corresponding N(1)-benzyltryptamine counterparts bind in a different fashion.     

Enzymic Preparation of Benzyl β-D-Glucopyranoside

Benzyl β-D-glucopyranoside was prepared by an enzyme-catalysed direct reaction between D-glucose, or better cellobiose, and benzyl alcohol in the presence of a minimum amount of water. The enzyme β-glucosidase was used in the immobilized form (adsorbed onto macroporous polyethylene terephthalate or covalently bound on polyglycidyl methacrylate), enabling multiple application.     

Simplified method for conjugating macrocyclic bifunctional chelating agents to antibodies via 2-iminothiolane

A one-step method for conjugating macrocyclic chelators to antibodies using the protein modification reagent 2-iminothiolane controls aggregation, maintains immunoreactivity, and produces consistent chelate/antibody ratios. Conjugation conditions have been investigated with the macrocyclic chelates 6-[p-(bromoacetamido)benzyl]-1,4,8,11-tetraazacyclotetradecane-N,N ',N",N"'-tetraacetic acid and 2-[p-(bromoacetamido)benzyl]-1,4,7,10-tetraazacyclododecane-N,N',N ",N"'-tetraacetic acid, with three different monoclonal antibodies. The bifunctional chelating agents are prepared by bromoacetylation of their amine precursors using a two-phase H2O/CHCl3 system, which improves product purity.     

The Auxinic Activity of Thioglycollic Acid Derivatives of β-Di-ketones

2,2′-Di(carboxymethylthio) pentan -4-one was found to increase the stem height of intact tomato plants growing in pots under glass. Stem height was increased by 60 percent although this was accompanied by malformations in lamina development, leaf epinasty, and a final reduction in shoot weight. Stem growth of tobacco and potato were also stimulated by this compound but the deleterious effects on leaf development were less marked. Subsequent screening of chemical analogues, using as an assay the growth response of intact tomato plants revealed that 3,3′-di(carboxymethylthio)heptan-5-one initially stimulated stem growth but then produced severe shoot damage, similar to that caused by phenoxyacetic acid herbicides. Both chemicals stimulated extension growth in a wheat coleoptile section test though to a lesser extent than indole-3-acetic acid. Like the carboxymethyl-N:N-dialkyldithiocarbamates, these straight chain compounds appear to possess true auxin activity that could be related to the formation of an incomplete unsaturated “ring” system.     

Benzyl alcohol dehydrogenase and benzaldehyde dehydrogenase II from Acinetobacter calcoaceticus. Purification and preliminary characterization.

A quick, reliable, purification procedure was developed for purifying both benzyl alcohol dehydrogenase and benzaldehyde dehydrogenase II from a single batch of Acinetobacter calcoaceticus N.C.I.B. 8250. The procedure involved disruption of the bacteria in the French pressure cell and preparation of a high-speed supernatant, followed by chromatography on DEAE-Sephacel, affinity chromatography on Blue Sepharose CL-6B and Matrex Gel Red A, and finally gel filtration through a Superose 12 fast-protein-liquid-chromatography column. The enzymes co-purified as far as the Blue Sepharose CL-6B step were separated on the Matrex Gel Red A column. The final preparations of benzyl alcohol dehydrogenase and benzaldehyde dehydrogenase II gave single bands on electrophoresis under non-denaturing conditions or on SDS/polyacrylamide-gel electrophoresis. The enzymes are tetramers, as judged by comparison of their subunit (benzyl alcohol dehydrogenase, 39,700; benzaldehyde dehydrogenase II, 55,000) and native (benzyl alcohol dehydrogenase, 155,000; benzaldehyde dehydrogenase II, 222,500) Mr values, estimated by SDS/polyacrylamide-gel electrophoresis and gel filtration respectively. The optimum pH values for the oxidation reactions were 9.2 for benzyl alcohol dehydrogenase and 9.5 for benzaldehyde dehydrogenase II. The pH optimum for the reduction reaction for benzyl alcohol dehydrogenase was 8.9. The equilibrium constant for oxidation of benzyl alcohol to benzaldehyde by benzyl alcohol dehydrogenase was determined to be 3.08 x 10(-11) M; the ready reversibility of the reaction catalysed by benzyl alcohol dehydrogenase necessitated the development of an assay procedure in which hydrazine was used to trap the benzaldehyde formed by the NAD+-dependent oxidation of benzyl alcohol. The oxidation reaction catalysed by benzaldehyde dehydrogenase II was essentially irreversible. The maximum velocities for the oxidation reactions catalysed by benzyl alcohol dehydrogenase and benzaldehyde dehydrogenase II were 231 and 76 mumol/min per mg of protein respectively; the maximum velocity of the reduction reaction of benzyl alcohol dehydrogenase was 366 mumol/min per mg of protein. The pI values were 5.0 for benzyl alcohol dehydrogenase and 4.6 for benzaldehyde dehydrogenase II. Neither enzyme activity was affected when assayed in the presence of a range of salts. Absorption spectra of the two enzymes showed no evidence that they contain any cofactors such as cytochrome, flavin, or pyrroloquinoline quinone. The kinetic coefficients of the purified enzymes with benzyl alcohol, benzaldehyde, NAD+ and NADH are also presented.     

Synthesis and antibacterial activity of N4-mono alkyl derivatives of novel glycopeptide LYV07ww01

Thirty-one N(4)-mono alkyl derivatives of novel glycopeptide LYV07ww01 were synthesized by the reductive alkylation and their in vitro antibacterial activity was tested. The benzyl derivatives showed potent activity, especially against vancomycin-resistant enterococci and penicillin-resistant Streptococcus pneumoniae.     

Enzymes of the mandelate pathway in bacterium N.C.I.B. 8250

1. Bacterium N.C.I.B. 8250 was grown on dl-mandelate, benzyl alcohol, benzoyl-formate, benzaldehyde and benzoate and also on 2-hydroxy, 4-hydroxy, 3,4-dihydroxy and 4-hydroxy-3-methoxy analogues of these compounds. The enzymic complements of the cells were determined and the specificities of some of the enzymes examined. 2. Growth on mandelate or benzoylformate induces l-mandelate dehydrogenase, benzoylformate decarboxylase, benzyl alcohol dehydrogenase and a heat-stable as well as a heat-labile benzaldehyde dehydrogenase. Growth on benzyl alcohol or benzaldehyde induces benzyl alcohol dehydrogenase and the heat-labile benzaldehyde dehydrogenase. 3. The enzymes of the mandelate-to-benzoate pathway are non-specifically active on, and induced by, all the substituted analogues that support growth. 4. Benzoate oxidase is induced by growth on benzoate or on 2-hydroxybenzoate. 2-Hydroxybenzoate hydroxylase, 4-hydroxybenzoate hydroxylase and 4-hydroxy-3-methoxybenzoate O-demethylase are induced only by growth on homologous substrates. 5. The results of the investigation are discussed with regard to the possible regulation of the enzyme systems.     

Improved access to 2-O-monobenzyl ethers of beta-cyclodextrin as precursors of catalysts for organophosphoryl esters hydrolysis

A comparative study of reaction conditions was performed for the synthesis of a 2-O-monobenzyl ether of cyclomaltoheptaose (beta-CD). Optimal conditions involved sodium ethoxide in Me(2)SO and benzyl bromide. The methodology was extended to the preparation of various 2(I)-O-iodobenzyl and 2(I)-O-carboxymethylbenzyl derivatives of beta-CD including a 3-carboxymethyl-4-iodobenzyl derivative of interest as precursor of an enzyme mimic to degrade the organophosphoryl ester diethyl 4-nitrophenyl phosphate (paraoxon).     

Small molecule inhibitors of the CCR2b receptor. Part 1: Discovery and optimization of homopiperazine derivatives

N,N'-Disubstituted homopiperazine derivatives have been discovered as CC-chemokine receptor 2b (CCR2b) inhibitors with submicromolar activity in the CCR2b binding assay. A 4-substituted benzyl group on one homopiperazine nitrogen was an important moiety for binding affinity to the CCR2b receptor. The SAR for CCR2b binding affinity correlated inversely with the sigma factor of the functional group on this benzyl moiety. Introduction of hydroxy groups to appropriate positions in the 3,3-diphenylpropyl group on the other homopiperazine nitrogen increased CCR2b binding activity. The synthesis of an informer library to search for alternative substructures is also described.     

Synthesis of phosphopeptides via global phosphorylation on the solid phase: Resolution of H-phosphonate formation

Summary The formation of the H-phosphonate by-products from the ‘global’ phosphorylation of a Thr-containing peptide resin using both di-t-butyl and dibenzylN,N-diethylphosphoramidite was identified to result from 1H-tetrazolemediated cleavage of thet-butyl or benzyl from the intermediate dialkyl phosphite triester and re-arrangement of the resultant hydroxy phosphite diester to the H-phosphonate form. This side reaction was rectified by the use of aqueous iodine for the oxidation step in which the H-phosphonate is oxidised to the benzyl phosphorodiester which, on acidolytic treatment, gives the desired dihydrogen phosphate.     

Carbonic anhydrase inhibitors: sulfonamides as antitumor agents?

Novel sulfonamide inhibitors of the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1) were prepared by reaction of aromatic or heterocyclic sulfonamides containing amino, imino, or hydrazino moieties with N,N-dialkyldithiocarbamates in the presence of oxidizing agents (sodium hypochlorite or iodine). The N,N-dialkylthiocarbamylsulfenamido-sulfonamides synthesized in this way behaved as strong inhibitors of human CA I and CA II (hCA I and hCA II) and bovine CA IV (bCA IV). For the most active compounds, inhibition constants ranged from 10(-8) to 10(-9) M (for isozymes II and IV). Three of the derivatives belonging to this new class of CA inhibitors were also tested as inhibitors of tumor cell growth in vitro. These sulfonamides showed potent inhibition of growth against several leukemia, non-small cell lung, ovarian, melanoma, colon, CNS, renal, prostate and breast cancer cell lines. With several cell lines. GI50 values of 10-75 nM were observed. The mechanism of antitumor action with the new sulfonamides reported here remains obscure, but may involve inhibition of CA isozymes which predominate in tumor cell membranes (CA IX and CA XII), perhaps causing acidification of the intercellular milieu, or inhibition of intracellular isozymes which provide bicarbonate for the synthesis of nucleotides and other essential cell components (CA II and CA V). Optimization of these derivatives from the SAR point of view, might lead to the development of effective novel types of anticancer agents.     

Synthesis and tripanocidal activity of ferrocenyl and benzyl diamines against Trypanosoma brucei and Trypanosoma cruzi

Trypanosoma brucei and Trypanosoma cruzi are the etiologic agents of sleeping sickness and Chagas disease, respectively, two of the 17 preventable tropical infectious diseases (NTD) which have been neglected by governments and organizations working in the health sector, as well as pharmaceutical industries. High toxicity and resistance are problems of the conventional drugs employed against trypanosomiasis, hence the need for the development of new drugs with trypanocidal activity. In this work we have evaluated the trypanocidal activity of a series of N1,N2-dibenzylethane-1,2-diamine hydrochlorides (benzyl diamines) and N1-benzyl,N2-methyferrocenylethane-1,2-diamine hydrochlorides (ferrocenyl diamines) against T. brucei and T. cruzi parasite strains. We show that incorporation of the ferrocenyl group into the benzyl diamines increases the trypanocidal activity. The molecules exhibit potential trypanocidal activity in vitro against all parasite strains. Cytotoxicity assay was also carried out to evaluate the toxicity in HepG2 cells.     

Effects of Ethyl and Benzyl Analogues of Spermine on Escherichia coli Peptidyltransferase Activity, Polyamine Transport, and Cellular Growth

Various ethyl and benzyl spermine analogues, including the anticancer agent N1,N12-bis(ethyl)spermine, were studied for their ability to affect the growth of cultured Escherichia coli cells, to inhibit [3H]putrescine and [3H]spermine uptake into cells, and to modulate the peptidyltransferase activity (EC 2. 3. 2. 12). Relative to other cell lines, growth of E. coli was uniquely insensitive to these analogues. Nevertheless, these analogues conferred similar modulation of in vitro protein synthesis and inhibition of [3H]putrescine and [3H]spermine uptake, as is seen in other cell types. Thus, both ethyl and benzyl analogues of spermine not only promote the formation and stabilization of the initiator ribosomal ternary complex, but they also have a sparing effect on the Mg2+ requirements. Also, in a complete cell-free protein-synthesizing system, these analogues at low concentrations stimulated peptide bond formation, whereas at higher concentrations, they inhibited the reaction. The ranking order for stimulation of peptide-bond formation by the analogues was N4,N9-dibenzylspermine > N4, N9-bis(ethyl)spermine congruent with N1-ethylspermine > N1, N12-bis(ethyl)spermine, whereas the order of analogue potency regarding the inhibitory effect was inverted, with inhibition constant values of 10, 3.1, 1.5, and 0.98 microM, respectively. Although the above analogues failed to interact with the putrescine-specific uptake system, they exhibited high affinity for the polyamine uptake system encoded by the potABCD operon. Despite this fact, none of the analogues could be internalized by the polyamine transport system, and therefore they could not influence the intracellular polyamine pools and growth of E. coli cells.